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Ocupaciones relacionadasSOC
Basado en la clasificación ocupacional SOC
| name | cis-ubuntu1804-v220-1-1-1-3 |
| description | Ensure mounting of jffs2 filesystems is disabled |
| category | cis-storage |
| version | 2.2.0 |
| author | cyberstrike-official |
| tags | ["cis","ubuntu","linux","ubuntu-18.04","filesystem","jffs2","kernel-module"] |
| cis_id | 1.1.1.3 |
| cis_benchmark | CIS Ubuntu Linux 18.04 LTS Benchmark v2.2.0 |
| tech_stack | ["ubuntu","linux"] |
| cwe_ids | [] |
| chains_with | [] |
| prerequisites | [] |
| severity_boost | {} |
Ensure mounting of jffs2 filesystems is disabled
Profile
Level 1 - Server / Level 1 - Workstation, Assessment: Automated
Description
The jffs2 (journaling flash filesystem 2) filesystem type is a log-structured filesystem used in flash memory devices.
Rationale
Removing support for unneeded filesystem types reduces the local attack surface of the system. If this filesystem type is not needed, disable it.
Impact
None noted.
Audit Procedure
Command Line
Run the following script to verify the jffs2 module is disabled. If the module is available in the running kernel:
- An entry including
/bin/true or /bin/false exists in a file within the /etc/modprobe.d/ directory
- The module is deny listed in a file within the
/etc/modprobe.d/ directory
- The module is not loaded in the kernel
If available in ANY installed kernel:
- The module is deny listed in a file within the
/etc/modprobe.d/ directory
#!/usr/bin/env bash
{
l_output="" l_output2="" l_output3="" l_dl=""
l_mname="jffs2"
l_mtype="fs"
l_searchloc="/lib/modprobe.d/*.conf /usr/local/lib/modprobe.d/*.conf /run/modprobe.d/*.conf /etc/modprobe.d/*.conf"
l_mpath="/lib/modules/**/kernel/$l_mtype"
l_mpname="$(tr '-' ' ' <<< "$l_mname")"
l_mndir="$(tr '-' '/' <<< "$l_mname")"
module_loadable_chk()
{
l_loadable="$(modprobe -n -v "$l_mname")"
[ "$(wc -l <<< "")" -gt ] && l_loadable=
grep -Pq -- <<< ;
l_output=
l_output2=
}
()
{
! lsmod | grep > /dev/null 2>&1;
l_output=
l_output2=
}
()
{
l_dl=
modprobe --showconfig | grep -Pq -- ;
l_output=
l_output2=
}
l_mdir ;
[ -d ] && [ -n ];
l_output3=
[ != ] && module_deny_chk
[ = ];
module_loadable_chk
module_loaded_chk
l_output=
[ -n ] && -e
[ -z ];
-e
-e
[ -n ] && -e
}
$l_loadable
"1"
"$(grep -P -- "(^\h*install|\b$l_mname)\b" <<< "$l_loadable")"
if
'^\h*install \/bin\/(true|false)'
"$l_loadable"
then
"$l_output\n - module: \"$l_mname\" is not loadable: \"$l_loadable\""
else
"$l_output2\n - module: \"$l_mname\" is loadable: \"$l_loadable\""
fi
module_loaded_chk
if
"$l_mname"
then
"$l_output\n - module: \"$l_mname\" is not loaded"
else
"$l_output2\n - module: \"$l_mname\" is loaded"
fi
module_deny_chk
"y"
if
'^\h*blacklist\h+'
"$l_mpname"
'\b'
then
"$l_output\n - module: \"$l_mname\" is deny listed in: \"$(grep -Pls -- "^\h*blacklist\h+$l_mname\b" $l_searchloc)\""
else
"$l_output2\n - module: \"$l_mname\" is not deny listed"
fi
for
in
$l_mpath
do
if
"$l_mdir/$l_mndir"
"$(ls -A $l_mdir/$l_mndir)"
then
"$l_output3\n - \"$l_mdir\""
"$l_dl"
"y"
if
"$l_mdir"
"/lib/modules/$(uname -r)/kernel/$l_mtype"
then
fi
else
"$l_output\n - module: \"$l_mname\" doesn't exist in \"$l_mdir\""
fi
done
"$l_output3"
echo
"\n\n -- INFO --\n - module: \"$l_mname\" exists in:$l_output3"
if
"$l_output2"
then
echo
"\n- Audit Result:\n ** PASS **\n$l_output\n"
else
echo
"\n- Audit Result:\n ** FAIL **\n - Reason(s) for audit failure:\n$l_output2\n"
"$l_output"
echo
"\n- Correctly set:\n$l_output\n"
fi
Expected Result
- module: "jffs2" is not loadable
- module: "jffs2" is not loaded
- module: "jffs2" is deny listed
Remediation
Command Line
If the module is available in the running kernel:
- Create a file with
install jffs2 /bin/false in the /etc/modprobe.d/ directory
- Create a file with
blacklist jffs2 in the /etc/modprobe.d/ directory
- Unload jffs2 from the kernel
If available in ANY installed kernel:
- Create a file with
blacklist jffs2 in the /etc/modprobe.d/ directory
If the kernel module is not available on the system or pre-compiled into the kernel:
- No remediation is necessary
#!/usr/bin/env bash
{
l_mname="jffs2"
l_mtype="fs"
l_mpath="/lib/modules/**/kernel/$l_mtype"
l_mpname="$(tr '-' ' ' <<< "$l_mname")"
l_mndir="$(tr '-' '/' <<< "$l_mname")"
module_loadable_fix()
{
l_loadable="$(modprobe -n -v "$l_mname")"
[ "$(wc -l <<< "$l_loadable")" -gt "1" ] && l_loadable="$(grep -P -- "(^\h*install|\b$l_mname)\b" <<< "$l_loadable")"
if ! grep -Pq -- '^\h*install \/bin\/(true|false)' <<< "$l_loadable"; then
echo -e "\n - setting module: \"$l_mname\" to be not loadable"
echo -e "install $l_mname /bin/false" >> /etc/modprobe.d/"$l_mpname".conf
fi
}
module_loaded_fix()
{
if lsmod | grep "$l_mname" > /dev/null 2>&1; then
echo -e "\n - unloading module \"$l_mname\""
modprobe -r "$l_mname"
fi
}
module_deny_fix()
{
if ! modprobe --showconfig | grep -Pq -- "^\h*blacklist\h+$l_mpname\b"; then
echo -e "\n - deny listing \"$l_mname\""
echo -e "blacklist $l_mname" >> /etc/modprobe.d/"$l_mpname".conf
fi
}
for l_mdir in $l_mpath; do
if [ -d "$l_mdir/$l_mndir" ] && [ -n "$(ls -A $l_mdir/$l_mndir)" ]; then
echo -e "\n - module: \"$l_mname\" exists in \"$l_mdir\"\n - checking if disabled..."
module_deny_fix
if [ "$l_mdir" = "/lib/modules/$(uname -r)/kernel/$l_mtype" ]; then
module_loadable_fix
module_loaded_fix
fi
else
echo -e "\n - module: \"$l_mname\" doesn't exist in \"$l_mdir\"\n"
fi
done
echo -e "\n - remediation of module: \"$l_mname\" complete\n"
}
Default Value
References
- NIST SP 800-53 Rev. 5: CM-7
CIS Controls
v8 - 4.8 Uninstall or Disable Unnecessary Services on Enterprise Assets and Software (IG 2, IG 3)
v7 - 9.2 Ensure Only Approved Ports, Protocols and Services Are Running (IG 2, IG 3)
MITRE ATT&CK Mappings: T1005, T1005.000 (TA0005) - M1050